1. Field of the Invention
The present invention relates to an image forming apparatus of an electrophotographic system such as a printer or a copying machine, and more particularly, to an image forming apparatus that uses a dry two-component development system and supplies a developer to a developing device by a toner supply device.
2. Description of the Related Art
Conventionally, in image forming apparatuses in which a two-component developer is used, a toner supply device is configured to supply an appropriate amount of toner to a developing device. Japanese Patent Laid-Open No. 2006-201576 discloses a system in which toner is determined not to be present by detecting that a decrease in the toner density of a developer is less than a threshold value by a predetermined number of times.
However, in the technology disclosed in Japanese Patent Laid-Open No. 2006-201576, a problem of a change in the image density is not sufficiently solved.
According to an examination of the applicants, it has been known that the temperature and humidity of a developer receive an influence of the temperature and humidity of supplied toner and the degree of the influence increases as differences of the temperature and humidity between the developer and the toner and the amount of supplied toner increase. This is a cause of the change in an image density which is a problem of the related art.
It is desirable to provide an image forming apparatus capable of suppressing a change in an image density caused due to the temperature and humidity of supplied toner.